东准噶尔贝勒库都克铝质A型花岗岩微量元素地球化学特征及地质意义

通过对新疆东准噶尔卡拉麦里地区贝勒库都克岩体的岩石地球化学特征的研究,结果表明,在贝勒库都克黑云母花岗岩中Rb、K和Th等大离子亲石元素明显富集,相对富集Zr、Hf等高场强元素,相对亏损Ba、Sr、Nb和Eu等元素,稀土元素含量相对较高,Eu的负异常极强,稀土元素配分模式呈平坦的“V”字型,属于典型的铝质A型花岗岩。该花岗岩在成因上属于A2型,形成于后碰撞的张性环境,其来源可能与洋壳和岛弧建造组成的年轻地壳有关。花岗岩微量元素构造判别图显示它是一种后碰撞花岗岩,标志卡拉麦里地区在晚石炭世造山作用的结束和板内构造演化的开始。该岩体锡质量分数普遍都比较高(15.50×10^-6),为锡的成矿物质来源和锡矿矿床学的深入探索提供重要参考。

Trace Elements Geochemistry Feature and Tectonic Significance of the Beilekuduke Aluminous A-type Granite in East Junggar

The geochemistry feature of rock in Beilekuduke granite in Kalamaili region of East Junggar, Xinjiang is discussed. The result shows that the biotite granites are typical aluminum A-type granites because of the enrichment of large-ion lithophile elements(Rb, K, Th, etc), relative enrichment of high field strength elements(Zr, Hf), relative loss of Ba, Sr, Nb, Eu, a high level of rare earth elements(REE), Eu negative anomaly extremely and flat “V” shaped of REE pattern. The granite is belong to A2-type originally and formed in the post-collision expansion environment, and may be derived from the young crust constructed by the oceanic crust and island arcs. Trace elements in granite tectonic discriminate diagram shows that it is a post-collisional granite, and indicates that the end of Late Carboniferous orogenesis in Kalamaili region and the start of plate tectonic evolution. The content of Sn, which is generally large(15.50×10^-6)in the granite, is very important for the study of tin mineral deposit and source.